Leftover Baked Potato Soup - Alton Brown

Ingredients

• 4 (10-ounce) leftover baked potatoes, halved width-wise
• 2 teaspoons olive oil
• 1 tablespoon plus 1/4 teaspoon kosher salt, divided
• 3 tablespoons butter
• 1 1/2 cups finely chopped leeks
• 2 tablespoons minced garlic
• 1 quart chicken or vegetable stock, hot
• 1 1/2 cups low-fat buttermilk
• 1/2 cup sour cream
• 1/2 cup freshly grated Parmesan cheese
• 1 teaspoon freshly ground black pepper
• 1 tablespoon sherry vinegar
• 1/4 cup minced chives